chore: add ruff, mypy, ESLint, and astro check quality tooling

- backend: add ruff>=0.4 and mypy>=1.10 to dev optional-dependencies
  with ruff config (E/W/F/I/UP/B rules, py311 target, 120 char line)
  and mypy config (ignore_missing_imports, check_untyped_defs)
- frontend: add eslint, typescript-eslint, eslint-plugin-astro as
  devDependencies; add 'check' (astro check) and 'lint' scripts
  scoped to PR #14 files only ([id]/index.astro, [id]/print.astro,
  src/lib/label-template.ts)
- frontend: create eslint.config.mjs with flat config for TS + Astro
- fix: replace @ts-ignore with @ts-expect-error in [id]/index.astro
  (QRCode UMD global) as required by @typescript-eslint/ban-ts-comment

Author: akira69

backend/pyproject.toml

@@ -29,6 +29,8 @@ dependencies = [
 dev = [
     "pytest>=7.4.0",
     "pytest-asyncio>=0.23.0",
+    "ruff>=0.4.0",
+    "mypy>=1.10.0",
 ]
 
 [build-system]
@@ -37,3 +39,23 @@ build-backend = "hatchling.build"
 
 [tool.hatch.build.targets.wheel]
 packages = ["app"]
+
+[tool.ruff]
+target-version = "py311"
+line-length = 120
+
+[tool.ruff.lint]
+select = ["E", "W", "F", "I", "UP", "B"]
+ignore = [
+    "B008",  # function calls in default args (FastAPI Depends pattern)
+    "E501",  # line too long
+]
+per-file-ignores = { "tests/**/*.py" = ["B"] }
+
+[tool.ruff.lint.isort]
+known-first-party = ["app"]
+
+[tool.mypy]
+python_version = "3.11"
+ignore_missing_imports = true
+check_untyped_defs = true

frontend/eslint.config.mjs

@@ -0,0 +1,16 @@
+import tseslint from 'typescript-eslint';
+import eslintPluginAstro from 'eslint-plugin-astro';
+
+export default tseslint.config(
+  ...tseslint.configs.recommended,
+  ...eslintPluginAstro.configs['flat/recommended'],
+  {
+    rules: {
+      '@typescript-eslint/no-explicit-any': 'warn',
+      '@typescript-eslint/no-unused-vars': ['warn', { argsIgnorePattern: '^_' }],
+    },
+  },
+  {
+    ignores: ['dist/', '.astro/'],
+  },
+);